Merge branch 'minor'

* minor:
  docs: "make distcheck" implementation details are not to be abused
  NEWS: improve and adjust in light of the oncoming 1.15 release
  shell-no-trail-bslash: improve diagnostic in case of failure

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

4 files changed, 74 insertions, 31 deletions

diff --git a/NEWS b/NEWS
index bb011a882..661112a7b 100644
--- a/NEWS
+++ b/NEWS
@@ -175,16 +175,43 @@ New in 1.15:
     extra useless "make all" recursive invocation in some corner cases
     (automake bug#16302).
 
-* Bugs fixed:
+* Distribution:
 
-  - The expansion of AM_INIT_AUTOMAKE ends once again with a trailing
-    newline (bug#16841).  Regression introduced in Automake 1.14.
+  - Automake bug#18286: "make distcheck" could sometimes fail to detect
+    missing files in the distribution tarball, especially in those cases
+    where both the generated files and their dependencies are explicitly
+    in $(srcdir).  An important example of this are *generated* makefile
+    fragments included at Automake time in Makefile.am; e.g.:
 
-  - The user can now extend the special .PRECIOUS target, the same way
-    he could already do with the .MAKE .and .PHONY targets.
+        ...
+        $(srcdir)/fragment.am: $(srcdir)/data.txt $(srcdir)/preproc.sh
+            cd $(srcdir) && $(SHELL) preproc.sh <data.txt >fragment.am
+        include $(srcdir)/fragment.am
+        ...
 
-  - Fixed confusing typos in the manual and in some warning messages
-    (automake bug#16827 and bug#16997).
+    If the use forgot to add data.txt and/or preproc.sh in the distribution
+    tarball, "make distcheck" would have erroneously succeeded!  This issue
+    is now fixed.
+
+  - As a consequence of the previous change, "make distcheck" will run
+    using '$(distdir)/_build/sub' as the build directory, rather than
+    simply '$(distdir)/_build' (as it was with Automake 1.14 and earlier).
+    Consequently, the './configure' and 'make' invocations issued by the
+    distcheck recipe will have $(srcdir) equal to '../..', rather than to
+    just '..' (as it was with Automake 1.14 and earlier).  Dependent and
+    similar variables (e.g., top_srcdir) are also changed accordingly.
+
+    Thus, Makefiles that made assumptions about the exact values of the
+    build and source directories used by "make distcheck" will have to
+    be adjusted.  Notice that making such assumptions was a bad and
+    unsupported practice anyway, since the exact locations of those
+    directories should be considered implementation details, and we
+    reserve the right to change them at any time.
+
+* Miscellaneous bugs fixed:
+
+  - The expansion of AM_INIT_AUTOMAKE ends once again with a trailing
+    newline (bug#16841).  Regression introduced in Automake 1.14.
 
   - We no longer risk to use '$ac_aux_dir' before it's defined (see
     automake bug#15981). Bug introduced in Automake 1.14.
@@ -205,21 +232,11 @@ New in 1.15:
     something like "... overrides Automake target '$(srcdir)/foo.am".
     This bug is now fixed.
 
-  - Automake bug#18286: "make distcheck" could sometimes fail to detect
-    missing files in the distribution tarball, especially in those cases
-    where both the generated files and their dependencies are explicitly
-    in $(srcdir).  An important example of this are *generated* makefile
-    fragments included at Automake time in Makefile.am; e.g.:
-
-        ...
-        $(srcdir)/fragment.am: $(srcdir)/data.txt $(srcdir)/preproc.sh
-            cd $(srcdir) && $(SHELL) preproc.sh <data.txt >fragment.am
-        include $(srcdir)/fragment.am
-        ...
+  - The user can now extend the special .PRECIOUS target, the same way
+    he could already do with the .MAKE .and .PHONY targets.
 
-    If the use forgot to add data.txt and/or preproc.sh in the distribution
-    tarball, "make distcheck" would have erroneously succeeded!  This issue
-    is now fixed.
+  - Fixed confusing typos in the manual and in some warning messages
+    (automake bug#16827 and bug#16997).
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -327,8 +344,8 @@ New in 1.14:
 
     Now that we have the 'info-in-builddir' option that explicitly causes
     generated '.info' files to be placed in the builddir, this hack should
-    be longer necessary, so we deprecate it with runtime warnings.  It will
-    be removed altogether in Automake 2.0.
+    be longer necessary, so we deprecate it with runtime warnings.
+    It will be removed altogether in Automake 2.0.
 
 * Relative directory in Makefile fragments:
 
diff --git a/doc/automake.texi b/doc/automake.texi
index 0a25baca1..016a1210e 100644
--- a/doc/automake.texi
+++ b/doc/automake.texi
@@ -1243,8 +1243,12 @@ uninstall} do not omit any file (@pxref{Standard Targets}),
 and it checks that @code{DESTDIR} installations work (@pxref{DESTDIR}).
 @end itemize
 
-All of these actions are performed in a temporary subdirectory, so
-that no root privileges are required.
+All of these actions are performed in a temporary directory, so that no
+root privileges are required.  Please note that the exact location and the
+exact structure of such a subdirectory (where the extracted sources are
+placed, how the temporary build and install directories are named and how
+deeply they are nested, etc.) is to be considered an implementation detail,
+which can change at any time; so do not rely on it.
 
 Releasing a package that fails @code{make distcheck} means that one of
 the scenarios we presented will not work and some users will be
@@ -8534,6 +8538,13 @@ finally, makes another tarball to ensure the distribution is
 self-contained.
 @end itemize
 
+All of these actions are performed in a temporary directory.  Please
+note that the exact location and the exact structure of such a directory
+(where the read-only sources are placed, how the temporary build and
+install directories are named and how deeply they are nested, etc.) is
+to be considered an implementation detail, which can change at any time;
+so do not reply on it.
+
 @vindex AM_DISTCHECK_CONFIGURE_FLAGS
 @vindex DISTCHECK_CONFIGURE_FLAGS
 @subheading DISTCHECK_CONFIGURE_FLAGS
diff --git a/t/ax/shell-no-trail-bslash.in b/t/ax/shell-no-trail-bslash.in
index 322495824..26979b617 100644
--- a/t/ax/shell-no-trail-bslash.in
+++ b/t/ax/shell-no-trail-bslash.in
@@ -26,6 +26,7 @@ am_SHELL=${AM_TESTSUITE_SHELL-'@SHELL@'}
 (
   set -e
   shell_command=; unset shell_command
+  shell_script=; unset shell_script
   while test $# -gt 0; do
     case $1 in
       # The shell might be invoked by make e.g. as "sh -ec" or "sh -ce".
@@ -40,7 +41,8 @@ am_SHELL=${AM_TESTSUITE_SHELL-'@SHELL@'}
 
   if test x${shell_command+"set"} != x"set"; then
     if test $# -gt 0; then
-      shell_command=$(cat "$1")
+      shell_script=$1
+      shell_command=$(cat <"$shell_script")
     else
       # Some make implementations, like *BSD's, pass the recipes to the
       # shell through its standard input.  Trying to run our extra checks
@@ -48,6 +50,7 @@ am_SHELL=${AM_TESTSUITE_SHELL-'@SHELL@'}
       exit 0
     fi
   fi
+  original_shell_command=$shell_command
 
   tab='	'
   nl='
@@ -59,10 +62,16 @@ am_SHELL=${AM_TESTSUITE_SHELL-'@SHELL@'}
 
   case "$shell_command" in
     *\\)
-      printf '%s\n' "$0: recipe/script ends with backslash character" >&2
-      printf '%s\n' "=== BEGIN recipe/script" >&2
-      printf '%s\n' "${am_shell_command-}" >&2
-      printf '%s\n' "=== END recipe/script" >&2
+      {
+        printf '%s\n' "$0: recipe/script ends with backslash character"
+        printf '%s\n' "=== BEGIN recipe/script"
+        if test x${shell_script+"set"} = x"set"; then
+          cat <"$shell_script"
+        else
+          printf '%s\n' "$original_shell_command"
+        fi
+        printf '%s\n' "=== END recipe/script"
+      } >&2
       exit 1
       ;;
   esac
diff --git a/t/self-check-shell-no-trail-bslash.sh b/t/self-check-shell-no-trail-bslash.sh
index 19198898b..8b7afa5c5 100644
--- a/t/self-check-shell-no-trail-bslash.sh
+++ b/t/self-check-shell-no-trail-bslash.sh
@@ -58,11 +58,17 @@ for sfx in \
 ; do
   for pfx in "" "echo bad" ": a${nl}# multine${nl}: text"; do
     cmd=${pfx}${sfx}
-    printf '%s\n' "$cmd" > bad.sh
+    printf '%s' "$cmd" > bad.sh
     for args in '-c "$cmd"' './bad.sh'; do
       eval "\$SHELL $args 2>stderr && { cat stderr >&2; exit 1; }; :"
       cat stderr >&2
       $FGREP "recipe/script ends with backslash character" stderr
+      cmd="$cmd" $PERL -w -e '
+        undef $/;
+        $_ = <>;
+        index($_, $ENV{cmd}) >= 0 or exit 1;
+      ' <stderr
+      $FGREP "$cmd" stderr
     done
   done
 done